I am having the same exact problem, and made the same comparison! I'm coming out of a Note 8 into this Note 10plus and I can't believe how horrible my picture quality is. I thought this phone would minimize my need for my actual camera, but sadly it's not the case
I upgraded from the Note 8 to the 10 and I said the exact same thing. But the 10 you have to manually go in and adjust the settings versus the Note 8 already being set up for you with awesome quality.
Check to if your display settings are set to max. They were on the note 8 but in the s9 and up they started changing the settings to full hd by default. You can change the screen res by going in to settings then display then make sure the screen resolution is set to max. Hope this helps.